AutoCodes – Generic – U2106

U2106 Code - Lost Communications With Transmission Control Module

Quick Answer

Modules connected to the Controller Area Network (CAN) serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Transmission Control Module (TCM), Transmission Control Module harness is open or shorted, Transmission Control Module circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: U2106 indicates Lost Communications With Transmission Control Module.
Common causes: Common causes include Faulty Transmission Control Module (TCM), Transmission Control Module harness is open or shorted, Transmission Control Module circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 10,206

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jun 15, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U2106 Description

Modules connected to the Controller Area Network (CAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module. A module with a CAN serial data circuits malfunction or which loses power during the current ignition cycle will have a Loss of Communication Diagnostic Trouble Code (DTC) set by other modules that depend on information from that failed module. If any of the CAN circuit are shorted to battery voltage, ground, or between them no communication is possible on the CAN serial data bus, a Diagnostic Trouble Code will set.

OBDII Code U2106 - Lost Communications With Transmission Control Module - AutoCodes.com — U2106 Code - Lost Communications With Transmission Control Module

What does this mean?

What are the Possible Causes of the DTC U2106?

Faulty Transmission Control Module (TCM)
Transmission Control Module harness is open or shorted
Transmission Control Module circuit poor electrical connection

How to Fix the DTC U2106?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U2106 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the U2106 code?

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Information for Specific Makes

U2106 Buick — Lost Communications With Transmission Control Module
U2106 Cadillac — Lost Communications With Transmission Control Module
U2106 Chevrolet — Lost Communications With Transmission Control Module
U2106 GMC — Lost Communications With Transmission Control Module
U2106 Saturn — Lost Communications With Transmission Control Module

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about U2106 Code

1. What does OBDII code U2106 mean?

U2106 indicates a loss of communication between the Transmission Control Module (TCM) and other modules, typically the Powertrain Control Module (PCM).

2. What are the common symptoms of code U2106?

Symptoms may include the check engine light or service light turning on, erratic shifting, failure to shift gears, or the vehicle going into limp mode.

3. What causes code U2106 to appear?

Common causes include wiring issues like damaged or corroded connectors, a faulty TCM, a malfunctioning PCM, or network communication errors on the CAN bus.

4. Can I drive my car with a U2106 code?

It is possible to drive, but you may experience performance issues like limited shifting or reduced speed. Driving in this condition could cause further damage, so itâ€™s best to address it promptly.

5. How do I diagnose a U2106 code?

Start by inspecting the TCM wiring and connectors for damage or corrosion. Use a scan tool to check for additional codes and test the communication signals on the CAN bus network.

6. What tools are needed to fix the U2106 code?

Youâ€™ll need a diagnostic scan tool, a multimeter for electrical testing, and possibly a wiring diagram specific to your vehicle to trace connections.

7. Can a bad battery cause a U2106 code?

Yes, a weak or failing battery can disrupt communication between modules and trigger the U2106 code.

8. How much does it cost to repair a U2106 code?

Repair costs vary depending on the issue, ranging from $50 for a simple wiring fix to over $1,000 if the TCM or PCM needs replacement.

9. Does the U2106 code always mean the TCM is bad?

No, the code signifies a communication issue, which could be caused by wiring problems, module failures, or network errors, not necessarily a faulty TCM.

10. Can I reset the U2106 code without repairs?

Clearing the code with a scan tool may work temporarily, but if the underlying issue isnâ€™t fixed, the code will likely return.